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DIPOL Weekly Review - TV and SAT TV, CCTV, WLAN

No. 5/2010 (Feb. 1, 2010)

Systems of artificial intelligence - the future of image analysis. The biggest problem with the image analysis is the uniqueness of the input parameters. The object is never the same - differently illuminated, appearing at various distances and angles. These and other conditions greatly hinder the identification of the objects, e.g. car license plates, human faces etc. The solution to that problem are artificial intelligence systems, including artificial neural networks. Neural networks are computational models of human nervous system built from the elementary cells called neurons. Their task is to receive, process, and transmit information. The input signals to the cells (neurons) are fed via "connectors" called synapses. Particular functionality of these "connections" is the possibility of "programming", which allows to match the strength (weights) of the connections in the network to produce a desired signal flow, depending on the importance of the signal.

The computer model of nervous system (artificial neural network) needs suitable structure, depending on the complexity of the problems processed - kind of the network (feedforward, recurrent) and the number of layers and neurons (nodes). In order to differentiate the impact of individual connections (synapses) between neurons depending on the information conveyed, there are introduced weights - numerical factors which increase the importance of certain impulses, reducing the weight of others. The essence of artificial neural networks is the ability to learn - modification of the weights using mathematical functions. With the increase in number of "learning loops", the effectiveness of solving tasks continually grows. In recognition of images, the first elements of the network (the input layer) take the values depending on the parameters of the image (e.g. pixel color). Transforming this information through successive neurons, the output layer provides information on decisions taken by the program - for example, detection of the face of a particular person or specified vehicle license number. Since the artificial neural networks are enhanced systems and well tolerate disturbances, they are suitable for use with a high level of random noise, or different kind of interference.

control of processes based on visual information, monitoring of human body, monitoring of machines etc. - recognition of emergencies.

Software based on neural networks allows, among other things, the analysis and prediction of crowd behavior

Decapolis - where are these antennas? Decapolis is the name of ten ancient cities. It was established after the conquest of Alexander the Great (around 332 BC), on a very important strategic territory. Then, to preserve the Hellenic influence in the region, the veterans of Alexander's army were among the settlers forming Greek colonies, further being reinforced by Greek-speaking immigrants. During the reign of the Syrian Seleucid dynasty (about 200 BC), it was a central part of the empire reaching from the Mediterranean to India and the territories ruled by Greek Ptolemies. In the year 63 BC Pompey conquered the region with Decapolis, and the Hellenistic cities came under Roman protectorate. Subjected to Rome, the cities had to pay taxes and send men to military service, but still could mint their own coins and retain considerable autonomy. Some of the cities, like Gadara (Umm Qais) shown in the pictures below, fell into disrepair (although the visible TV antennas are the evidence that life is coming back), others continue to exist. Two of the former Decapolis cities have become the capitals of modern states.

Which of the former Decapolis cities are capitals of modern states? You can check your answer at the end of this issue.

Gadara - one of the cities of Dekapol - a state of ruin.

Ancient buildings are used for bars and shops - hence the antennas visible in the pictures.

Which of the former Decapolis cities are capitals of modern states? - You can find out at the end of this issue.

F connectors - important components of antenna installations. Every connector, even of top quality, causes additional loss of signal, so the number of connections should be limited to real needs. A good manufacturer of connectors provides two important parameters determining the signal loss. The first is called voltage standing wave ratio (VSWR), indicating how much of the power of the signal is reflected back to the source of signal. In the case of satellite IF the parameter should not exceed 1.5, which means that ca. 4% of the signal power comes back to the source. The second is insertion loss (attenuation) - its value should not exceed 0.2 dB, or approximately 0.5% of the signal power. The connectors used outdoors have to be protected against penetration of water. It is so important because even a drop of water would increase VSWR even by several tens of percent, changing energy of the signal into heat. The connector Platinum (E80274) has been designed to ensure watertightness (after crimping) both from the side of the cable and the device. During compression of the connector another plastic bush is tightly pressed against the sheath of the cable (by putting on cone brass case - the compression ring). The plastic material is protected by patent Delrin of well known for quality of products DuPont company. It is UV-proof, and ensures stable physical parameters in very wide temperature range. The metal parts of the connector made of nickel-plated brass are corrosion-proof.

Satellite meter/finder with DVB-S receiver and A/V monitor for CCTV. WS-6906 R10820 meter allows to quickly setup satellite dishes and LNBs. Using the built-in satellite tuner, the user can check on the screen the quality of reception of specific FTA channels. The meter is especially useful during installation of multiswitch systems, allowing the measurement of signal level, BER and C/N. This enables the user to select (at the design stage) and verify (during implementation) the equipment (dish, LNBs, amplifiers, multiswitches). During startup of the installation the device allows to localize possible problems. Large installations with multiswitches require the use of multi-stage amplification, which introduces additional noise. As is known, the increase in the level of noise associated with the deterioration of the signal directly translates into increase of BER. BER values above 10-4 in the subscriber outlet practically prevent reception, because the decoder will not be able to restore the original signal. For proper reception, the BER level at the LNB output should be not higher than 10-8. A/V input allows connecting CCTV cameras, making the device a very useful tool for installers of video surveillance systems. The installer can precisely set the focal length and focus of each camera.

How to combine SAT and terrestrial TV signals? Installations where a single cable distributes radio, terrestrial and satellite TV broadcasts are currently the most commonly used type of distribution network. The best solution is combining the signals from the three sources already at the input of the system. Despite the fact that these signals are distributed at different frequencies, they cannot be combined with the use of typical combiners/splitters.

In the case of small individual installations with one or two TV/SAT outlets (R694100), the cheapest and most convenient solution will be the use of TV/SAT Combiner - Splitter. The device allows to combine the signals and to transmit power to the LNB and optionally (like R85310) to the preamplifier/s of terrestrial signals.

It should be noted that both the LNB and amplifier are powered from the satellite receiver. If there is no need to power an preamplifier, the option is the use of high-class TV/Sat Combiner/Diplexer from TERRA - R85300. In the case of placing TV/SAT combiner/s outdoors (e.g. on a mast), the suitable devices are R85311 and R85312.

In larger installations, the simplest and at the same time the most professional solution for combining the signals is to use multiswitch which can provide signals to many outlets (from several to several dozen).

Video transmission from several analog cameras through a single cable. Each of the installers at least once experienced the problem of sending signals from several analog cameras through a single cable. Often this is due to the fact that the site is equipped with some kind of wiring - a UTP/FTP, coaxial, or fiber optic cable (single-mode or multimode). It is worth to utilize the existing cabling.

The RF modulator MDP-4S has been originally designed for distribution in antenna system up to four A/V signals coming from various sources e.g. sat receivers, CCTV cameras. It is used mainly for distribution of CCTV images within MATV/SMATV systems, but can be employed in any CCTV installation, allowing to transmit four video and audio channels through single coaxial cable at distances up to 100 meters.

UTP/FTP cable - 4-channel video transmission is enabled by Active Video Transmitter ATT-4 M16674 cooperating with Active Video Receiver ART-4 M16675. In video paths the transmitter matches the impedance of coaxial cables (75 ohm) to the impedance of twisted pairs (100 ohm) and amplifies the signals. Each video channel uses one twisted pair. The advantage of the solution is low price and the possibility of sending the signals over distances up to 2 kilometers (CAT5 cable).

fiber optic cable - transmission of signals from 4 analog cameras via a fiber optic cable can be performed by using 4-channel video converters of ULTIMODE series. The examples are the ULTIMODE converter sets V-204D L2421 (for a single-mode fiber) and V-024D L2402 (for a multimode fiber). The big advantages of optical technology are the immunity to electromagnetic interference and long distances at which the signals can be transmitted (for single-mode fibers - 20km, for multimode fibers - 2 km).

It is worth noting that transmission of analog signals through a single cable is efficient and economic solution, allowing users to save on cabling costs.

BABY TV - a new application of IP cameras. In the University Hospital Carl Gustav Carus in Dresden, Germany, there have been installed IP cameras directed at the incubators in the room for premature infants. The system called Baby TV serves to maintain contact between parents and the child. In this way, the mother from another room can view and listen to what is going on with her baby. Thanks to connection to the Internet, also other family members can watch the baby from any place in the world. This solution also reduces the workload for doctor and nurses - the parents and family can see and hear their baby any moment without having to call the personnel at the hospital. The system employs megapixel IP cameras ACTi ACM-4201 K1514, providing images of 1.3 Mpix resolution and sound. The installation company that implemented the solution in the hospital has already completed a similar installation in Berlin, and is ready to mount such systems in other hospitals.

Damascus - the capital of Syria, and Amman - the capital of Jordan. The Decapolis included: Damascus, Philadelphia (modern Amman), Rafana, Scythopolis (modern Beit She'an), Gadara, Hippos, Dion, Pella, Gerasa (modern Jerash), Canatha. The cities were located in ancient Palestine - a strategic region that since ancient times was of significant importance for the rulers seeking dominion over Asia and Africa.

Three cities of Decapolis - from the left: Damascus - Umayyad Mosque,

Amman - view from the Citadel Hill, Jerash - Roman ruins.

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